Determining the efficacy of liquid sporicides against spores of Bacillus subtilis on a hard nonporous surface using the quantitative three step method: collaborative study.

A collaborative study was conducted to validate the quantitative Three Step Method (TSM), designed to measure the performance of liquid sporicides on hard nonporous surfaces. Ten laboratories participated in the study. The goals were to evaluate the repeatability and reproducibility of the LR values, to estimate the components of variance for LR, and assess method responsiveness. AOAC Method 966.04-Method II was used as reference method. The test chemicals used were sodium hypochlorite, a combination of peracetic acid and hydrogen peroxide, and glutaraldehyde. Each test chemical was evaluated at 3 levels of presumed efficacy: high, medium, and low. J AOAC Int. 2008;91(4):833-52.